Purification of acylated polypeptide coating aids



United States Patent '0 "ice 7 2,824,015 PURIFICATION or AYL-ATEUPoLYPEi rmE- COATING AIDS Kodak Company, Rochester, N; Y.", acorporation of New Jersey No Drawing, Application-May 27, 1955 Serial N.511,800 Claims. (Cl. 166-455;

This invention relates to a method of removing the impurities fromacylated polypeptides which are employed as coating aids in themanufacture of photographic products.

It is often desirable particularly in the photographic industry to applyone or more layers of gelatin to a surface. In applying gelatin coatingsit is often desirable to incorporate in the gelatin coating compositiona coating aid to improve the properties of that material in the coatingoperation. Saponin has been commonly employed for that purpose butrecently it has been found desirable to incorporate synthetic coatingaids included among which are the acylated polypeptides. The use ofthese materials as coating aids in gelatin coating compositions isdescribed and claimed in Knox and Wright application Ser. No. 383,388,filed September 30, 1953.

Heretofore in the use of these materials in gelatin coating compositionsthe material has been prepared and the entire resulting mass from thatpreparation has been added to the gelatin coating composition. Althoughthis practice has been satisfactory in many applications of gelatincoatings, there has been up to now no useful method of purifying thesematerials and thus their use in some cases demanding high purity hasleft something to be desired.

It is one object of my invention to provide a method of purifyingacylated polypeptide coating aids so as to remove impurities therefromwhich might hinder their use in certain critical operations. Anotherobject of my invention is to prepare the purified acylated polypeptidesin a form in which they may be readily employed in gelatin compositions.A further object of my invention is to prepare purified acylatedpolypeptides Without any derogatory efI'ect thereon. Other objects of myinvention will appear herein.

The above objects are readily accomplished by first forming with theacylated polypeptide a mixture with gelatin such that the resultingcomposition essentially consists of 25-75% of gelatin and 75-25% ofacylated polypeptide based on the gelatin-polypeptide derivativemixture. In usual practice equal parts of the gelatin and polypeptidederivatives result in a mixture which may be conveniently purified.After the mixture of gelatin and acylated polypeptide is prepared it isset by chilling and formed into small size units such as by forcing theset mass through small perforations to form noodles or the like. Theonly qualification is that the units formed are of sufficient strengthto keep their shape upon washing with cold water.

The washing may be carried out to the extent desired depending upon thepurity wanted. A washing time of 2 to 4 hours is usually ample to obtaina satisfactorily pure product. The washing and drying of the materialcan be conveniently carried out by forming layers of the noodledmaterial on a foraminous screen which may be slowly moved along under aWater spray, the speed of wash and the length wherein the noodles aresprayed being governed by the desired washing time. After the materialhas 2,824,615 wee levat-ed temperature may be passedthrough the gelatinnoodles upon the foraminou's belt for a sufficie'nt time to caused'r'yingof the noodles: Another rfithod of washing which may be employedis to collect the nfo'odiesfin ttiiesh container which may be dippedinto water preferably while in motion so that noodles are reduced intheir content of salts or other impurities which might b presenttherein.The washed noodles can if desiredbe' put baguette" at nets and allowedto stand exposed to the airparticula'rly of low relative humiditywirqe'ti mmsture is reniovedfrom the noodles or other iinit's. Thewashed material may be employed in photographic emulsions and isparticularly valuable for use in highly sensitive emulsions such asemulsions of the high speed negative type due to its being free offogging and desensitizing materials and essentially free of inorganicsalts such as sodium chloride, sodium sulfate and the like.

The materials which may be purified by my invention are the acylatedlower polypeptides particularly those of l-lO peptide groups which havebeen acylated with aliphatic acid halides of 8-18 carbon atoms. Some ofthe materials which may be purified by my procedure are those preparedby methods described in patents such as U. S. Patents Nos. 2,015,912;2,041,265; 2,113,819 and Br. Patent No. 413,016. Some of the compoundswhich may be so purified are the reaction products of polypeptides ofthe types referred to and oleoyl, lauroyl, palmitoyl, myristoyl,capryloyl, pelaragonyl and ricinoleyl chlorides. The reaction isordinarily carried out in the presence of a base so that the productformed may be a salt of the acylated polypeptide. The following exampleillustrates my invention:

Example A solution of 5 lbs. 11 ozs. of bone gelatin and 22 lbs. ofwater was warmed to 60 C. accompanied by agitation and added thereto was33 lbs. 13 ozs. of the mass resulting from preparing oleoyl polypeptidein which 16.9% of that material was present, the latter also warmed to60 C. The mass was stirred for 30 minutes so as to assure thoroughmixing of the gelatin and the oleoyl polypeptide and was chilledovernight. A solid gel mass formed. This mass was passed through aperforated plate forming noodles which were washed with water for 3hours and were dried by passing a current of warm dry air therethrough.The noodles obtained weighed 8 lbs. 13 ozs. The purified oleoylpolypeptide was employed as a coating aid both for photographicemulsions and in other types of aqueous gelatin coating compositions. Itwas found that the gelatin compositions containing the purified oleoylpolypeptide coated out readily and that the emulsions which had beenmixed with this material and coated exhibited no adverse effects fromthe coating aid which had been purified in accordance with my invention.

Instead of oleoyl polypeptide any one of the other acylated polypeptidesas referred to may be purified in a like manner. Ordinarily thepolypeptides which are employed in making acylated polypeptides are madeup of a mixture of materials of varying numbers of peptide groups in themolecule. Most of these materials, however, have a peptide group contentwithin the range of 1-10 peptide groups.

I claim:

1. A method of refining a water soluble acylated polypeptide, the acylof which comprises aliphatic acid radicals of 8-l8 carbon atoms and thepeptide group content of which is within the range of l-lO, theimpurities of which include inorganic salts, which comprisesincorporating in the acylated polypeptide an aqueous solution of gelatinin the proportion of 75-25% of the former and 25-75% of the latter,based on the solid weight of the mixture, chilling the resulting mixtureto form a solid gel mass therefrom, dividing the mass into small unitsand washing with cold water to substantially reduce the salt content ofthe acylated polypeptide.

2. A method of refining a water soluble acylated polypeptide, the acylof which comprises aliphatic acid radicals of 8-18 carbon atoms and thepeptide group content of which is within the range of 1-10, theimpurities of which include inorganic salts, which comprises mixing withthe acylated polypeptide an equal amount of gelatin in aqueous solution,all based on solid weight, chilling the resulting mixture to form asolid gel mass therefrom, dividing the mass into small units and washingwith cold water to substantially reduce the salt content of the acylatedpolypeptide.

3. A method of refining a water soluble oleoyl polypeptide, the peptidegroup content of which is within the range of 1-10, the impurities ofwhich include inorganic salts, which comprises incorporating into theoleoyl polypeptide, an aqueous solution of gelatin in the proportion of75-25% of the former and 25-75% of the latter, based on dry weight,chilling the resulting mixture to form a solid gel mass therefrom,dividing the mass into small units and washing with cold water tosubstantially reduce the salt content of the oleoyl polypeptide.

References Cited in the file of this patent UNITED STATES PATENTS2,719,146 Schwander Sept. 27, 1955 2,729,628 Mann Jan. 3, 1956 2,763,639Elins et al. Sept. 18, 1956

1. A METHOD OF REFINING A WATER SOLUBLE ACYLATED POLYPEPTIDE, THE ACYLOF WHICH COMPRISES ALIPAHTIC ACID RADICALS OF 8-18 CARBON ATOMS AND THEPEPTIDE GROUP CONTENT OF WHICH IS WITHIN THE RANGE OF 1-10, THEIMPURITIES OF WHICH INCLUDE INORGANIC SALTS, WHICH COMPRISESINCORPORATING IN THE ACYLATED POLYPEPTIDE AN AQUEOUS SOLUTION OF GELATININ THE PROPORTION OF 75-25% OF THE FORMER AND 25-75% OF THE LATTER,BASED ON THE SOLID WEIGHT OF THE MIXTURE, CHILLING THE RESULTING MIXTURETO FORM A SOLID GEL MASS THEREFROM, DIVIDING THE MASS INTO SMALL UNITSAND WASHING WITH COLD WATER TO SUBSTANTIALLY REDUCE THE SALT CONTENT OFTHE ACYLATED POLYPEPTIDE.